1. Field of the Invention
The present invention relates generally to dental instruments used for cleaning and polishing teeth. More particularly, the invention relates to a dental prophylaxis angle and handpiece assembly. The dental prophylaxis angle is removably attached to the dental handpiece by a new interlocking mechanism.
2. Brief Description of the Related Art
Today, dental professionals use dental instruments commonly known as dental prophylaxis (prophy) angles for cleaning and polishing teeth. Referring to FIG. 1, traditional prophy angles (10) include a one-piece or multi-piece tubular housing (12) having sleeve (14), neck (16), and head (18) portions. Normally, the head portion (18) extends at an angle of ninety (90) degrees with respect to the neck portion (16). However, in some cases, contra-prophy angles having a head portion that extends at an angle of greater than 90 degrees are used. Dental professionals use the contra-prophy angles for cleaning hard-to-reach tooth surfaces. In both types of prophy angles, the tubular housing contains a relatively long drive shaft (20) having a driving gear (22) at its forward-facing end. The driving gear (22) of the drive shaft interacts with a driven gear (24) located in the head (18) of the prophy angle. A boss (25), which is located on top of the driven gear, is adapted for receiving a prophy cup or other dental tool. The driven gear (24) is integrally connected to a relatively short shaft (26).
The prophy angle (10) is attached to a dental handpiece (30) by inserting the drive shaft (20) into a chuck system (32) such as a collet or other retaining means in the handpiece, for example, ISO 3964 locking system. In addition, the sleeve portion (14) of the prophy angle contains a slot (15) which is adapted for receiving a standard positioning pin or finger (not shown) on the handpiece. The extended slot (15) permits the free end of the prophy angle to expand. The chuck jaws (32) hold the shaft (20) in place and operatively couples the shaft to an electrical or air-driven motor inside of the handpiece. The chuck jaws (32) rotate on anti-friction ball bearings (34) in the handpiece. When an operator powers on the handpiece, the connected drive shaft of the prophy angle rotates and the driving gear (22) intermeshes with the driven gear (24). This causes the prophy angle to rotate along with the attached prophy cup.
The prophy cup, which is filled with prophy paste, is pressed against the tooth surfaces to clean and polish the teeth. Different prophy pastes can be used depending upon the dental health of the patient and amount of dental plaque and calculus that needs to be removed. For example, NUPRO® prophylaxis paste, available from Dentsply International (York, Pa.) can be used as the prophy paste, and this paste is available in different textures (fine, medium, and coarse) depending upon the size of the abrasive particles used in the paste. Fluoride-containing and fluoride-free prophy pastes are available. A professional cleaning with prophy paste helps prevent dental caries caused by bacteria in dental plaque. Bacteria produce acids that eat into the tooth eventually causing cavities to form therein. When the teeth are cleaned and polished by a dental professional, the dental plaque can be effectively removed from the tooth surfaces of the patient. In addition, calculus build-up and extrinsic stains caused by beverages and food such as, for example, coffee, tea, or soda, also can be effectively removed. The prophy angles are normally made from an inexpensive, flexible plastic and the prophy cup is made from a rubbery material. The dental professional disposes the prophy angles and cups after one-time use on a patient.
There are numerous dental prophy angles and prophy pastes systems known in the dental field including, for example, Upgrade® disposable prophy angles (Sultan Dental Products); All Pro® disposable prophy angles (Young Dental Manufacturing Colo.); and NUPRO Revolv® disposable prophy angles (Dentsply International). Different handpiece connection systems for attaching the prophy angles are described in the patent literature.
For example, Kivlighan, U.S. Pat. No. 5,348,473 discloses a medical tool such as a dental prophylaxis angle. The housing is made of two plastic halves which snap-fit together. The right-hand housing portion includes ridges that project into the cavities of the left-hand housing portion. The housing portions are connected by pushing them towards each other so that the ridges on the first housing portion project into the cavities of the opposing housing portion. The locking ridges are forced into the locking cavities to maintain the two portions in their locked position.
Bailey, U.S. Pat. No. 5,531,599 discloses plastic, easy-to-assemble dental prophylaxis contra-angles, wherein the head of the prophy angle is angled at an angle greater than 90 degrees with respect to the handpiece. An elongated slot in the body of the prophy angle permits the body to be force-fit onto a standard dental handpiece. The body of the prophy angle can be slipped over the nose of a handpiece, such as a Doriot type handpiece having a collet, which receives the drive shaft of the angle.
Bailey, U.S. Pat. No. 5,683,247 discloses a maintenance-free dental prophylaxis angle comprising a one-piece body including a sleeve and a head. The angle is designed to be used for an extended period of time, for example, one year without requiring any lubrication. The angle includes an internal lubricant circulating system. A slit is cut into the sleeve of the prophy angle and this creates two spring fingers which expand slightly when the angle is placed on a handpiece. This creates a size-on-size frictional fit with the nose of the handpiece and it to hold the prophy angle body independently of the handpiece chuck.
Kraenzle, U.S. Pat. No. 6,203,322 discloses a dental prophy angle having a forward end formation with a hinged closure that allows access to the gears and drive shaft inside of the angle. The closure is secured in a fixed position on the forward end formation by locking elements. The prophy angle includes a drive shaft that drives a rotor in the head of angle. The drive shaft is driven by a driving mechanism in a dental handpiece and the prophy angle is attached to the handpiece in a conventional fashion.
Conventional dental prophy angles and handpiece systems are generally effective; however, there is a need for an improved system. Traditional systems can have some drawbacks. For example, after prolonged use and excessive vibrational motion, some drive shafts of some prophy angles can shear off in the handpiece. The broken-off drive shaft can be difficult to remove from the handpiece and normally it must be returned to the factory for repair. Another problem with some conventional prophy angle and handpiece systems is that the prophy angle shows poor stability when it is mounted on the handpiece. Some prophy angles tend to wobble and rock. The prophy angles have excessive lateral movement. This can cause significant problems when the prophy angle/handpiece assembly is being used during a cleaning procedure. A dental professional may feel uncomfortable using such an unstable prophy angle/handpiece assembly, and it may cause added anxiety for the user and patient being treated.
Thus, there is a need in the dental industry for a prophy angle and handpiece assembly which is more stable and feels more comfortable. The assembly should have a good ergonomic design and be durable and lightweight. It is important that the prophy angle and handpiece assembly have good dimensional stability so that the prophy angle does not wobble and rock freely while it is being used. The prophy angle should be locked securely onto the handpiece. At the same time, a dental professional should be able to remove the prophy angle easily in order to substitute a new prophy angle in place thereof as needed. The present invention provides such a prophy angle and handpiece assembly having these objects, features, and advantages as well as others.